In mechanical transmission devices of the epicyclic gear train type, the planet carrier carries a plurality of planets that are mounted on the planet carrier via respective rotation shafts.
In order to avoid said rotation shafts performing interfering movements relative to the planet carrier, a stop ring is generally associated with each rotation shaft to prevent the corresponding rotation shaft moving axially.
Unfortunately, it can happen during assembly of the epicyclic gear train that the operator forgets to put one or more stop rings into place or does not do so properly. Because of the small size of the stop rings, one or more forgotten or wrongly placed stop rings are not always detected.
This can lead to a degraded epicyclic gear train being put into operation.